Reduced thickness cover

ABSTRACT

A unitary cover is used with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary cover comprises a central circular wall of a size corresponding to the container open end. A concentric ring region surrounds the central circular wall and defines a peripheral flange having a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container. The peripheral flange has a substantially greater wall thickness than the central circular wall

FIELD OF THE INVENTION

This invention relates to a drum cover and, more particularly, to a cover of reduced wall thickness.

BACKGROUND OF THE INVENTION

In one form of conventional shipping and storage container, a drum comprises a tubular container having an open end with a cylindrical connecting bead at the open end. The connecting bead may be provided by a metal connecting ring rolled onto the side wall or a plastic connecting ring molded directly to or otherwise adhered to the side wall. Alternatively, the side wall may be of molded plastic construction with an integral connecting bead.

The conventional drum includes a removable cover for closing the open end of the tubular side wall. A typical cover includes a central circular wall with a peripheral connecting flange receivable on the connecting bead so that the circular wall closes the open end of the container. A locking band secures the cover on the drum. While such a container may be used for storage purposes, often the containers must be lifted by lifting equipment. Advantageously, the drum should be designed to accommodate parrot beak drum lifting devices. If the cover is not of sufficient thickness, the drum may not pass a typical parrot beak test. Typically, such a cover includes circular channels or rings formed in the circular wall providing a corrugated or wave-like appearance.

A typical cover is formed of molded synthetic resin, such as high density polyethylene. In designing such a cover, consideration may be given to minimizing weight and cost of the cover while also satisfying test requirements. As such, a conventional cover is manufactured having a wall thickness sufficient to pass a parrot beak test. A typical cover for a 21½″ drum has a wall thickness on the order of 0.09″ nominal. Lesser thickness covers have been considered, but have not always successfully passed this test.

The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a cover for use with a tubular container including areas of different wall thickness.

Broadly, in accordance with one aspect of the invention, there is disclosed a unitary cover used with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary cover comprises a central circular wall of a size corresponding to the container open end. A concentric ring region surrounds the central circular wall and defines a peripheral flange having a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container. The peripheral flange has a substantially greater wall thickness than the central circular wall.

It is a feature of the invention that the cover comprises a wall thickness nominally about 0.09 inches for the peripheral flange and a wall thickness nominally 0.06 inches for the central circular wall.

It is another feature of the invention that the concentric ring region comprises first and second concentric rings disposed between the peripheral flange and the central circular wall to define a generally corrugated structure.

It is still another feature of the invention that wall thickness of the concentric ring region gradually decreases transitioning from the peripheral flange to the central circular wall.

It is still another feature of the invention that the peripheral flange has a wall thickness about 50% greater then wall thickness of the central circular wall.

There is disclosed in accordance with another aspect of the invention a unitary cover for use with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary cover comprises a central circular wall of a size corresponding to the container open end, a plurality of concentric rings surrounding the central circular wall and including a peripheral flange having a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container, the peripheral flange having a substantially greater wall thickness than the central circular wall.

It is a feature of the invention that the plurality of concentric rings comprises first and second concentric rings disposed between the peripheral flange and the central circular wall to define a generally corrugated structure.

It is a further feature of the invention that the first concentric ring has a greater wall thickness than the central circular wall and the second concentric ring has a greater wall thickness than the second concentric ring and the peripheral flange has a greater wall thickness than the second concentric ring rib.

It is still another feature of the invention that the peripheral flange has a diameter to be received on a tubular container having an, 18 inch, a 21½ inch or a 23 inch connecting bead.

It is still a further feature of the invention that the cover comprises a unitary wall element of synthetic resin.

There is disclosed in accordance with another aspect of the invention a unitary cover for use with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary cover comprises a central circular wall of a size corresponding to the container open end, a series of concentric rings surrounding the central circular wall and defining a corrugated structure, an outermost ring comprising a peripheral flange having a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container, the peripheral flange having a substantially greater wall thickness than the central circular wall.

Further features and advantages of the invention will be readily apparent from the specification and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a container including a cover according to the invention;

FIG. 2 is a sectional view of the cover of FIG. 1 taken along a line 2-2;

FIG. 3 is a sectional view, similar to FIG. 2, for a cover according to an alternative embodiment of the invention; and

FIG. 4 is a detailed sectional view of a left portion of the sectional view of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

In the illustrated embodiment of the invention, as disclosed in FIG. 1, a shipping and storage container in the form of a drum 12 includes a tubular side wall 14 closed by a bottom wall (not shown) and having an open end 16 to define an interior space 18. A cylindrical connecting bead 20 is at the open end 16. The open end 16 is selectively closed by a closure in the form of a cover 22 in accordance with the invention removably secured to the connecting bead 20 with a locking band 24.

In the illustrated embodiment of the invention, the drum 12 comprises a cylindrical, blow-molded plastic drum. The drum has a capacity of 55 U.S. gallons and the connecting bead 20 has a diameter of about 21½″. As is apparent, the dimensions of the drum 12 may vary and other typical dimensions of the connecting bead 20 are about 18″ and 23″. The present invention is directed particularly to the cover 22 which can be used with drums of other construction, such as metal, fiberboard, or composite construction, as will be apparent.

Referring to FIG. 2, the cover 22 is illustrated in greater detail. The cover 22 is sized to be used with any one of an 18″, 21½″ or 23″ drum. As is apparent other sizes could also be used. The cover 22 comprises a unitary wall element of molded synthetic resin, such as high density polyethylene. The cover 22 includes a central circular wall 26. The central circular wall 26 comprises a circular planar panel 28 of a size corresponding to the container open end 16. A pair of conventional threaded bung openings 30 and 32 are provided in the panel 28. The central circular wall 26 is surrounded by a concentric ring region 34 comprising a series of concentric rings 36, 37 and 38 stamped or molded integrally with the cover 22. The concentric rings 36-38 define a generally corrugated or wavelike structure around the periphery of the central circular wall 26. The inner rings 36 and 37 provide stiffening and expansion. The outermost ring 38 defines a peripheral flange having a downwardly opening annular channel 40 for receiving the connecting bead 20.

The circular panel 28 has a flat upper surface 42 having a peripheral edge 44. The first concentric ring 36 is radially outwardly of the peripheral edge 44 and is generally an inverted V-shape having a longer side 46 joined to the center wall peripheral edge 44 and a shorter side 48. The second concentric ring 37 is radially outwardly of the first concentric ring 36 and is generally an inverted V-shape having a shorter side 50 and a longer side 52. The shorter side 50 is joined to the first concentric ring shorter side 48 at a lower peak 54.

The peripheral flange 38 is radially outwardly of the second concentric ring 37. The peripheral flange 54 comprises a downwardly opening U-shaped wall portion 56 connected by a curved wall 58 to the second concentric ring 37 at a lower edge 60 of the second concentric ring longer side 52. The U-shaped wall portion 56 defines the downwardly opening channel 40 receivable on the cylindrical connecting bead 20 to close the open end 16 of the container 12. Particularly, and with reference to FIG. 4, an annular gasket 62 is positioned in the channel 40. The gasket 62 is seated on the connecting bead 20. The locking band 24 sandwiches the U-shaped wall portion 56, gasket 62 and connecting bead 20 to retain the cover 22 on the drum 12 in a conventional manner.

In accordance with the invention, the cover 22 is adapted to use a reduced wall thickness in non-critical areas, while maintaining a standard wall thickness in critical areas. Such a cover is adapted to pass conventional parrot beak tests.

Particularly, the central circular wall 26 has a first wall thickness. The walls of the peripheral flange 38 have a second wall thickness substantially greater than the thickness of the central circular wall 26. In accordance with the invention, the peripheral wall thickness is about 50% greater than the central circular wall thickness. In an illustrative embodiment of the invention, the wall thicknesses are nominally 0.09″ and 0.06″. As will be apparent, the wall thickness at edges may be slightly less to provide draft for mold purposes. In this embodiment of the invention the first and second concentric rings 36 and 37 have the same wall thickness as the central circular wall 26. The transition between wall thicknesses occurs at a transition point 64 proximate the peak 60.

With a conventional 21½″ cover of uniform 0.09″ wall thickness weight is about 1.85 lbs. A corresponding cover in accordance with the just described embodiment of the invention has a weight of about 1.1 lbs.

FIG. 3 illustrates a cover 122 according to an alternative embodiment of the invention. The cover 122 has similar elements to those of the cover 22 and are renumbered by adding 100 to the reference numbers from FIG. 2. The cover 122 includes wall thickness of the concentric ring region 134 gradually decreasing transitioning from the peripheral flange 138 to the central circular wall 126. Particularly, the first concentric ring 136 has a greater wall thickness than the central circular wall 126 and the second concentric ring 137 has a greater wall thickness than the first concentric ring 136 and the peripheral flange 138 has a greater wall thickness than the second concentric ring 137.

With the cover 122, transitions occur at points labeled T. Wall thickness of the peripheral flange 138 is A; of the second concentric ring longer side 152 is B; of the second concentric ring shorter side 150 and first concentric ring shorter side 148 is C; of the first concentric ring longer side 146 is D; and of the central circular wall 126 is E. In one embodiment of the invention the dimensions are A=0.09″; B=0.08″; C=0.075″; D=0.065″ and E=0.06″.

Thus, in accordance with the invention, there is provided a unitary cover including reduced wall thickness in non-critical areas to reduce weight. 

1. A unitary cover for use with a tubular container having an open end with a cylindrical connecting bead at the open end, the unitary cover comprising: a central circular wall of a size corresponding to the container open end, a concentric ring region surrounding the central circular wall and defining a peripheral flange having a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container, the peripheral flange having a substantially greater wall thickness than the central circular wall.
 2. The unitary cover of claim 1 wherein the cover comprises a wall thickness nominally about 0.09 inches for the peripheral flange and a wall thickness nominally 0.06 inches for the central circular wall.
 3. The unitary cover of claim 1 wherein the concentric ring region comprises first and second concentric rings disposed between the peripheral flange and the central circular wall to define a generally corrugated structure.
 4. The unitary cover of claim 3 wherein wall thickness of the concentric ring region gradually decreases transitioning from the peripheral flange to the central circular wall.
 5. The unitary cover of claim 1 wherein the peripheral flange has a wall thickness about 50% greater then wall thickness of the central circular wall.
 6. A unitary cover for use with a tubular container having an open end with a cylindrical connecting bead at the open end, the unitary cover comprising: a central circular wall of a size corresponding to the container open end, a plurality of concentric rings surrounding the central circular wall and including a peripheral flange having a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container, the peripheral flange having a substantially greater wall thickness than the central circular wall.
 7. The unitary cover of claim 6 wherein the cover comprises a wall thickness nominally about 0.09 inches for the peripheral flange and a wall thickness nominally 0.06 inches for the central circular wall.
 8. The unitary cover of claim 6 wherein the plurality of concentric rings comprises first and second concentric rings disposed between the peripheral flange and the central circular wall to define a generally corrugated structure.
 9. The unitary cover of claim 8 wherein wall thickness of the concentric ring region gradually decreases transitioning from the peripheral flange to the central circular wall.
 10. The unitary cover of claim 6 wherein the peripheral flange has a wall thickness about 50% greater then wall thickness of the central circular wall.
 11. The unitary cover of claim 8 wherein the first concentric ring has a greater wall thickness than the central circular wall and the second concentric ring has a greater wall thickness than the first concentric ring and the peripheral flange has a greater wall thickness than the second concentric ring.
 12. The unitary cover of claim 6 further comprising a pair of bung openings in the central circular wall.
 13. The unitary cover of claim 6 wherein the peripheral flange has a diameter to be received on a tubular container having an, 18 inch, a 21½ inch or a 23 inch connecting bead.
 14. The unitary cover of claim 6 wherein the cover comprises a unitary wall element of synthetic resin.
 15. A unitary cover for use with a tubular container having an open end with a cylindrical connecting bead at the open end, the unitary cover comprising: a central circular wall of a size corresponding to the container open end, a series of concentric rings surrounding the central circular wall and defining a corrugated structure, an outermost ring comprising a peripheral flange having a downwardly opening channel receivable on the cylindrical connecting bead to close the open end of the container, the peripheral flange having a substantially greater wall thickness than the central circular wall.
 16. The unitary cover of claim 15 wherein the cover comprises a wall thickness nominally about 0.09 inches for the peripheral flange and a wall thickness nominally 0.06 inches for the central circular wall.
 17. The unitary cover of claim 15 wherein wall thickness of the series of concentric rings gradually decreases transitioning from the peripheral flange to the central circular wall.
 18. The unitary cover of claim 15 wherein the peripheral flange has a wall thickness about 50% greater then wall thickness of the central circular wall.
 19. The unitary cover of claim 15 wherein a first concentric ring has a greater wall thickness than the central circular wall and a second concentric ring has a greater wall thickness than the first concentric ring and the peripheral flange has a greater wall thickness than the second concentric ring.
 20. The unitary cover of claim 15 wherein the cover comprises a unitary wall element of synthetic resin. 